An example of methods of synthesizing fluorine-containing ether includes a method in which fluorine-containing alkyl alcohol is allowed to react with fluorinated olefin in water in the presence of a basic compound such as an alkali metal compound to prepare fluorine-containing ether at yield of not less than 91% (Patent Documents 1 and 2). However, in these reactions, since a basic compound is present in a reaction system, dehydrohalogenation reaction from fluorine-containing ether as a target product inevitably simultaneously proceeds as a side reaction, and as a result, a compound having an unsaturated bond is produced as a by-product in an amount of about 0.1% by mass to about 10% by mass. Further, since a boiling point of this by-product having an unsaturated bond is close to a boiling point of a target fluorine-containing ether, there is a problem that separation by distillation is difficult.
Accordingly, in Patent Document 3, the use of a phase transfer catalyst is proposed as a method of lessening this side reaction, and fluorine-containing ether is obtained at a conversion ratio of 99.99% and at purity of 97.8%. However, in this method, cost is high since an expensive phase transfer catalyst is used.
In Patent Document 4, a reaction is carried out in the presence of a secondary alcohol or a tertiary alcohol, and fluorine-containing ether is obtained at a conversion ratio of 99.99% and at purity of 99.0%. However, in this method, cost is high since a secondary alcohol or a tertiary alcohol is used.
On the other hand, there is proposed, for example, a method of adding chlorine to a compound having an unsaturated bond to form a chlorine-adduct and then conducting separation as a method of increasing purity of fluorine-containing ether from the viewpoint of separation of this by-product having an unsaturated bond (Patent Document 5). However, in this method, since light and high temperature are needed, there is a problem that apparatus such as high pressure mercury lamp are required and the number of steps is increased.